Table 2.

Maximal rates and magnesium affinities for the individual chemical steps of ligation

	WT	R641L	R771W
k cat (s−1)	0.69 ± 0.10 *	0.27 ± 0.05 *	0.18 ± 0.03 *
k transfer (s−1)	3.0 ± 0.6 †	0.8 ± 0.1	0.46 ± 0.07
k seal (s−1)	16 ± 4 †	5.3 ± 0.3	7.0 ± 1.4
K Mg (mM)	0.86 ± 0.03 *	4.3 ± 1.5 *	3.5 ± 0.4 *
K Mg,transfer (mM)	0.10 ± 0.03 †	3.9 ± 0.4	6.1 ± 1.0
K Mg,seal (mM)	4.9 ± 2.1 †	13 ± 6	17 ± 8

Rate constants for single-turnover ligation were measured using rapid chemical quench (Figure 5). Values are the mean ± SD (n ≥ 3).*Values for k_cat and K_Mg are from (18). ^†Values for WT LIG1 are from (22).